Objective: This study is a first attempt to manipulate group norms and assess their impact on willingness to help victims of intimate partner violence. Method: Two studies were conducted, the first involving 218 undergraduates who read a newspaper article extract describing an intimate partner violence case, followed by the manipulation of morality-based in-group norms: importance of providing help, support, and report (experimental group) versus doing nothing (control condition). Participants were asked about their willingness to help the victim. Study 2 was conducted with 216 police officers to test the effect of moral in-group norms on their willingness to arrest the alleged perpetrator and assist the victim. Results: Findings from both studies showed that respondents increased their willingness to help the victim and provide support when they strongly identified with the in-group. Conclusion: The decision to intervene to help the victim is based on high identification with own-group social norms, but only for those police and lay people who do identify with the reference group. These results are central for bystander intervention and awareness campaigns and training programs for police. (PsycINFO Database Record (c) 2014 APA, all rights reserved)